Some online users reported being able to access the pages again – but there have not yet been any official announcements on a complete fix.
Outage website Downdetector earlier noted a spike in user reports relating to the services, which share backend infrastructure, about 2.45am AEST.
Facebook has since issued an updated statement.
“To everyone who was affected by the outages on our platforms today: we’re sorry,” Facebook Australia and New Zealand head of communications Antonia Sanda said.
“We know billions of people and businesses around the world depend on our products and services to stay connected. We appreciate your patience as we come back online.”
On Twitter, Facebook policy communications director Andy Stone earlier said the company was aware of the reported problems and “working to get things back to normal as quickly as possible”.
The New York Times reports Facebook has now sent a team to one of its California data centres to manually reset the server.
The cause of the outage is still unknown.
However, multiple security experts pointed to a Domain Name System problem as a possible culprit.
The company did not say what might be causing the outage.
Facebook’s own site would not load at all; Instagram and WhatsApp were accessible, but could not load new content or send messages.
Technology expert Trevor Long told Today he thinks the outage is a technical error, but couldn’t completely rule out the chance it was an attack.
He expected the issue could persist for hours.
“At a glance, it’s been down for a couple of hours now, at a glance I would potentially guess it’s a DNS error,” he told Today.
“It’s been a couple of hours already, which makes me think that it’s not a simple error at their end, actually.
“It’s the worst time for them. Morning here, afternoon in America and evening in Europe.
“This is the worst possible time, which also fuels the rumours and thoughts it could be an attack.
“Think about the number of people in governments or otherwise that use WhatsApp as a communication tool.
“So what you’ve done by disabling Facebook is disable communication between a lot of people who are now reverting to other systems.”
It is normal for websites and apps to suffer outages, though one on a global scale it is rare.
Regarding the internal failures, Adam Mosseri, the head of Instagram, tweeted that it feels like a “snow day.”
Users reported being unable to access Facebook in the USA and Europe, as well as Australia.
Facebook’s internal systems used by employees also went down.
Doug Madory, director of internet analysis for Kentik Inc., said it appears that the routes Facebook advertise online that tell the entire internet how to reach its properties are not available.
Mr. Madory said it looks like the DNS routes that Facebook makes available to the networking world have been withdrawn.
The Domain Name System is an integral element of how traffic on the internet is routed.
DNS translates an address like “facebook.com” to an IP address like 220.127.116.110.
If Facebook’s DNS records have disappeared, no one could find it.
Meanwhile, amid the outage, social media rival, Twitter, posted: “hello literally everyone.”
Facebook is going through a major crisis after the whistleblower who was the source of a series of The Wall Street Journal stories exposing the company’s awareness of internal research into the negative effects of its products and decisions went public on 60 Minutes in the US on Sunday.
Frances Haugen was identified in the interview as the woman who anonymously filed complaints with federal law enforcement that the company’s own research shows how it magnifies hate and misinformation, leads to increased polarisation and that Instagram, specifically, can harm teenage girls’ mental health.
The Journal‘s stories, called “The Facebook Files,” painted a picture of a company focused on growth and its own interests instead of the public good.
Ms Haugen, released thousands of pages of internal documents to regulators and the Wall Street Journal, is set to testify before a Senate subcommittee on Tuesday.
Facebook has tried to play down the research.
Nick Clegg, the company’s vice president of policy and public affairs, wrote to Facebook employees in a memo on Friday that “social media has had a big impact on society in recent years, and Facebook is often a place where much of this debate plays out.”
US shares of Facebook were down more than 5 per cent in midday trading on Monday (early Tuesday AEST), putting it on pace for its worst trading day in nearly a year.